Citroen has issued a silent campaign to change spark plugs of Puretech engines.
Cacti scheduled for annual service are getting new spark plugs for free, courtesy of the manufacturer.
I guess that Citroen has accumulated enough complaints worldwide concerning engine rattling,

No. The bonnet latch was a safety recall obligatory by law to be advertised.
All manufacturers send worldwide hundreds of Technical Service Bulletins per year. Ie TSB. Some of them are requesting the dealer to send you a letter and invite you for the service. Some of them are carried out when you enter annually for your Service. Thus it is called by the garage insiders a silent campaign.